Introduce APIs for hooking up display implementations

Introduce krun_set_display for specifying the amount of displays and their resoultion.
Introduce the the krun_set_display_backend for specifying the display backend as
a vtable and a bitmask of features. This also introduces a new header
libkrun_display.h and a krun_display rust crate which serves as a bidirectional
bindings for the C display API.

Signed-off-by: Matej Hrica <[email protected]>

Author: mtjhrc

Cargo.lock

@@ -1,5 +1,6 @@
 [workspace]
 members = ["src/libkrun"]
+exclude = ["examples/gtk_display"]
 resolver = "2"
 
 [profile.dev]

Cargo.toml

@@ -1,4 +1,5 @@
 LIBRARY_HEADER = include/libkrun.h
+LIBRARY_HEADER_DISPLAY = include/libkrun_display.h
 
 ABI_VERSION=1
 FULL_VERSION=1.14.0
@@ -145,6 +146,7 @@ install: libkrun.pc
 	install -d $(DESTDIR)$(PREFIX)/$(LIBDIR_$(OS))/pkgconfig
 	install -d $(DESTDIR)$(PREFIX)/include
 	install -m 644 $(LIBRARY_HEADER) $(DESTDIR)$(PREFIX)/include
+	install -m 644 $(LIBRARY_HEADER_DISPLAY) $(DESTDIR)$(PREFIX)/include
 	install -m 644 libkrun.pc $(DESTDIR)$(PREFIX)/$(LIBDIR_$(OS))/pkgconfig
 	install -m 755 $(LIBRARY_RELEASE_$(OS)) $(DESTDIR)$(PREFIX)/$(LIBDIR_$(OS))/
 	cd $(DESTDIR)$(PREFIX)/$(LIBDIR_$(OS))/ ; ln -sf $(KRUN_BINARY_$(OS)) $(KRUN_SONAME_$(OS)) ; ln -sf $(KRUN_SONAME_$(OS)) $(KRUN_BASE_$(OS))

Makefile

@@ -6,6 +6,7 @@ extern "C" {
 #endif
 
 #include <inttypes.h>
+#include <stddef.h>
 #include <stdbool.h>
 #include <unistd.h>
 
@@ -488,6 +489,103 @@ int32_t krun_set_gpu_options2(uint32_t ctx_id,
                               uint32_t virgl_flags,
                               uint64_t shm_size);
 
+/* Maximum number of displays. Same as VIRTIO_GPU_MAX_SCANOUTS defined in the virtio-gpu spec */
+#define KRUN_MAX_DISPLAYS 16
+
+/**
+ * Configure a display output for the VM.
+ *
+ * Note that to have display output a display backend must also be set (see krun_set_display_backend).
+ *
+ * Arguments:
+ *  "ctx_id"      - the configuration context ID.
+ *  "width"       - the width of the window/display
+ *  "height"      - the height of the window/display
+ *
+ * Returns:
+ *  The id of the display (0 to KRUN_MAX_DISPLAYS - 1) on success or a negative error number on failure.
+ */
+int32_t krun_add_display(uint32_t ctx_id, uint32_t width, uint32_t height);
+
+/**
+ * Configure refresh rate for a display
+ *
+ *
+ * Arguments:
+ *  "ctx_id"      - the configuration context ID.
+ *  "display_id"  - the ID of the display (range: 0 to KRUN_MAX_DISPLAYS - 1)
+ *  "refresh_rate" - refresh rate (in Hz)
+ *
+ * Returns:
+ *  Zero on success or a negative error number on failure.
+ */
+int32_t krun_display_set_refresh_rate(uint32_t ctx_id, uint32_t display_id, uint32_t refresh_rate);
+
+
+/**
+ * Configure physical size of the display reported to the guest
+ *
+ * This overrides the DPI set by krun_set_display_dpi()
+ *
+ * Arguments:
+ *  "ctx_id"      - the configuration context ID.
+ *  "display_id"  - the ID of the display (range: 0 to KRUN_MAX_DISPLAYS - 1)
+ *  "width_mm"    - width of the display in millimeters
+ *  "height_mm"   - height of the display in millimeters
+ *
+ * Returns:
+ *  Zero on success or a negative error number on failure.
+ */
+int32_t krun_display_set_physical_size(uint32_t ctx_id, uint32_t display_id, uint16_t width_mm, uint16_t height_mm);
+
+
+/**
+ * Configure DPI of the display reported to the guest
+ *
+ * This overrides the physical size of the display set by krun_set_display_physical_size()
+ *
+ * Arguments:
+ *  "ctx_id"      - the configuration context ID.
+ *  "display_id"  - the ID of the display (range: 0 to KRUN_MAX_DISPLAYS - 1)
+ *  "dpi"         - DPI (PPI) dots/pixels per inch of the display
+ *
+ * Returns:
+ *  Zero on success or a negative error number on failure.
+ */
+int32_t krun_display_set_dpi(uint32_t ctx_id, uint32_t display_id, uint32_t dpi);
+
+/**
+ * Configure a custom EDID blob for a display
+ *
+ * This replaces the generated EDID with a custom one. Configuring an EDID blob makes all display parameters except
+ * width and height ignored.
+ *
+ * Note that libkrun doesn't do any checks if the EDID matches the width/height specified in krun_add_display().
+ *
+ * Arguments:
+ *  "ctx_id"      - the configuration context ID.
+ *  "display_id"  - the ID of the display (range: 0 to KRUN_MAX_DISPLAYS - 1)
+ *  "edid_blob"   - the EDID blob
+ *  "blob_size"   - the size of the blob in bytes
+ *
+ * Returns:
+ *  Zero on success or a negative error number on failure.
+ */
+int32_t krun_display_set_edid(uint32_t ctx_id, uint32_t display_id, const uint8_t* edid_blob, size_t blob_size);
+
+/**
+ * Configures a krun_display_backend struct to be used for display output. (see libkrun_display.h)
+ *
+ * Arguments:
+ *  "ctx_id"          - the configuration context ID
+ *  "display_backend" - Pointer to a krun_display_backend struct
+ *  "backend_size"    - sizeof() the krun_display_backend struct
+ *
+ * Returns:
+ *  Zero on success or a negative error number (errno) on failure.
+ */
+int32_t krun_set_display_backend(uint32_t ctx_id, const void *display_backend, size_t backend_size);
+
 /**
  * Enables or disables a virtio-snd device.
  *

include/libkrun.h

@@ -0,0 +1 @@
+../src/krun_display/libkrun_display.h

include/libkrun_display.h

@@ -1,7 +1,6 @@
 // Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-#[allow(deref_nullptr)]
 #[allow(clippy::all)]
 #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
 pub mod x86;

src/arch_gen/src/lib.rs

@@ -11,7 +11,7 @@ tdx = ["blk", "tee"]
 net = []
 blk = []
 efi = ["blk", "net"]
-gpu = ["rutabaga_gfx", "thiserror", "zerocopy", "zerocopy-derive"]
+gpu = ["rutabaga_gfx", "thiserror", "zerocopy", "zerocopy-derive", "krun_display"]
 snd = ["pw", "thiserror"]
 virgl_resource_map2 = []
 nitro = []
@@ -31,6 +31,7 @@ virtio-bindings = "0.2.0"
 vm-memory = { version = ">=0.13", features = ["backend-mmap"] }
 zerocopy = { version = "0.6.3", optional = true }
 zerocopy-derive = { version = "0.6.3", optional = true }
+krun_display = { path = "../krun_display", optional = true, features = ["bindgen_clang_runtime"] }
 
 arch = { path = "../arch" }
 utils = { path = "../utils" }

src/devices/Cargo.toml

@@ -13,7 +13,9 @@ use super::defs;
 use super::defs::uapi;
 use super::defs::uapi::virtio_gpu_config;
 use super::worker::Worker;
+use crate::virtio::display::DisplayInfo;
 use crate::virtio::InterruptTransport;
+use krun_display::DisplayBackend;
 #[cfg(target_os = "macos")]
 use utils::worker_message::WorkerMessage;
 
@@ -44,12 +46,16 @@ pub struct Gpu {
     #[cfg(target_os = "macos")]
     map_sender: Sender<WorkerMessage>,
     export_table: Option<ExportTable>,
+    displays: Box<[DisplayInfo]>,
+    display_backend: DisplayBackend<'static>,
 }
 
 impl Gpu {
     pub(crate) fn with_queues(
         queues: Vec<VirtQueue>,
         virgl_flags: u32,
+        displays: Box<[DisplayInfo]>,
+        display_backend: DisplayBackend<'static>,
         #[cfg(target_os = "macos")] map_sender: Sender<WorkerMessage>,
     ) -> super::Result<Gpu> {
         let mut queue_events = Vec::new();
@@ -76,11 +82,15 @@ impl Gpu {
             #[cfg(target_os = "macos")]
             map_sender,
             export_table: None,
+            displays,
+            display_backend,
         })
     }
 
     pub fn new(
         virgl_flags: u32,
+        displays: Box<[DisplayInfo]>,
+        display_backend: DisplayBackend<'static>,
         #[cfg(target_os = "macos")] map_sender: Sender<WorkerMessage>,
     ) -> super::Result<Gpu> {
         let queues: Vec<VirtQueue> = defs::QUEUE_SIZES
@@ -90,6 +100,8 @@ impl Gpu {
         Self::with_queues(
             queues,
             virgl_flags,
+            displays,
+            display_backend,
             #[cfg(target_os = "macos")]
             map_sender,
         )
@@ -201,7 +213,7 @@ impl VirtioDevice for Gpu {
         let config = virtio_gpu_config {
             events_read: 0,
             events_clear: 0,
-            num_scanouts: 0,
+            num_scanouts: self.displays.len() as u32,
             num_capsets: 5,
         };
 
@@ -255,6 +267,8 @@ impl VirtioDevice for Gpu {
             #[cfg(target_os = "macos")]
             self.map_sender.clone(),
             self.export_table.take(),
+            self.displays.clone(),
+            self.display_backend,
         );
         worker.run();
 

src/devices/src/virtio/gpu/device.rs

@@ -0,0 +1,59 @@
+use krun_display::{
+    DisplayBackendBasicFramebuffer, DisplayBackendError, DisplayBackendNew, Rect, ResourceFormat,
+};
+use virtio_bindings::virtio_gpu::VIRTIO_GPU_MAX_SCANOUTS;
+
+#[derive(Clone, Debug)]
+pub struct DisplayInfo {
+    pub width: u32,
+    pub height: u32,
+}
+
+pub const MAX_DISPLAYS: usize = VIRTIO_GPU_MAX_SCANOUTS as usize;
+
+pub type DisplayInfoList = [Option<DisplayInfo>; MAX_DISPLAYS];
+
+impl DisplayInfo {
+    pub fn new(width: u32, height: u32) -> Self {
+        DisplayInfo { width, height }
+    }
+}
+
+pub struct NoopDisplayBackend;
+
+impl DisplayBackendNew<()> for NoopDisplayBackend {
+    fn new(_userdata: Option<&()>) -> Self {
+        Self
+    }
+}
+
+impl DisplayBackendBasicFramebuffer for NoopDisplayBackend {
+    fn configure_scanout(
+        &mut self,
+        _scanout_id: u32,
+        _display_width: u32,
+        _display_height: u32,
+        _width: u32,
+        _height: u32,
+        _format: ResourceFormat,
+    ) -> Result<(), DisplayBackendError> {
+        Err(DisplayBackendError::InvalidScanoutId)
+    }
+
+    fn disable_scanout(&mut self, _scanout_id: u32) -> Result<(), DisplayBackendError> {
+        Err(DisplayBackendError::InvalidScanoutId)
+    }
+
+    fn alloc_frame(&mut self, _scanout_id: u32) -> Result<(u32, &mut [u8]), DisplayBackendError> {
+        Err(DisplayBackendError::InvalidScanoutId)
+    }
+
+    fn present_frame(
+        &mut self,
+        _scanout_id: u32,
+        _frame_id: u32,
+        _rect: Option<&Rect>,
+    ) -> Result<(), DisplayBackendError> {
+        Err(DisplayBackendError::InvalidScanoutId)
+    }
+}

src/devices/src/virtio/gpu/display.rs

@@ -1,4 +1,5 @@
 mod device;
+pub mod display;
 mod event_handler;
 mod protocol;
 mod virtio_gpu;